A vast number of commercial products that are difficult to produce synthetically may be produced by fermentation. Such products include alcohols (e.g., ethanol, methanol, butanol, 1,3-propanediol); organic acids (e.g., citric acid, acetic acid, itaconic acid, lactic acid, gluconic acid, gluconate, succinic acid, 2,5-diketo-D-gluconic acid); ketones (e.g., acetone); amino acids (e.g., glutamic acid); gases (e.g., H2 and CO2), and more complex compounds, including, for example, antibiotics (e.g., penicillin and tetracycline); enzymes; vitamins (e.g., riboflavin, B12, beta-carotene); and hormones. Fermentation is also commonly used in the consumable alcohol (e.g., beer and wine), dairy (e.g., in the production of yoghurt and cheese), leather, and tobacco industries.
The yield of fermentation processes have been increased significantly over the last decade.
CA 1,143,677 discloses a process of producing ethanol by fermenting in the presence of ferments of amylolytic or cellulolytic action.
U.S. Pat. No. 5,231,017 disclose a process of producing ethanol, wherein a protease is introduced during saccharification.
WO 01/62947 discloses a process of producing ethanol wherein a phytase is added during fermentation
WO 02/38787 discloses a process of producing ethanol by fermentation, wherein secondary liquefaction is carried out in the presence of a thermostable acid alpha-amylase or a thermostable Maltogenic acid alpha-amylase.
WO 02/074895 discloses a process of producing a fermentation product, wherein fermentation is carried out in the presence of at least one carbohydrate-source generating enzyme and at least one alpha-amylase.
There is a need for further improvement of fermentation product processes, such as ethanol manufacturing processes.